Apparatus for measurement optical characteristic of a display panel

ABSTRACT

An ambient temperature control apparatus used for measuring ambient temperature. The apparatus has a bottom plate, a panel fitting apparatus, an external mask, and a temperature control device. The panel fitting apparatus is disposed on the bottom plate and is suitable for use to fix a liquid crystal panel. The external mask is detachably mounted on the bottom plate to form a cavity, in which the panel fitting apparatus and the liquid crystal panel are enclosed. The external mask includes at least a window allowing the photometer to measure the liquid crystal panel therefrom. The temperature control device mounted to the external mask is suitable to control the temperature variation of the cavity.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of a prior application Ser. No.10/248,199, filed Dec. 26, 2002 now U.S. Pat. No. 6,877,896.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates in general to a temperature control apparatus, andmore particular, to an ambient temperature control apparatus used formeasuring a liquid crystal display. The ambient temperature control isoperative to change the ambient temperature of the liquid crystal panel,so as to prevent it from affecting the ambient temperature of themeasurement equipment; therefore, the precision of the measurementequipment is ensured.

2. Related Art of the Invention

Having the features of small volume, light weight, low driving voltage,low power consumption, and portability, the liquid crystal displayproducts have been broadly applied. The application extends fromproducts from daily life to high-end industrial production, includingclocks, watches, computers, televisions, communication products, medicalinstrument, aviation transportation, industrial equipment, and specialarmaments. The high-quality liquid crystal displays tend to graduallyreplace the conventional color cathode ray tubes.

The conventional fabrication process of liquid crystal displays includesthe following steps. A glass substrate is cleaned (pre-cleaningprocess). An indium tin oxide (ITO) conductive layer is formed on theglass substrate (pattern process). An alignment film is formed on theconductive layer (alignment and pattern transfer process). A spacer isformed between the two glass substrates. An insulating epoxy resinmaterial is printed around the glass substrates (sealant coatingprocess). The substrates are then adhered to each other (assembly andsealing process), and cut into individual dies. The liquid crystal isinjected and the assembled substrates are then sealed by pressure,followed by the processes of corner rounding of the glass substrates,inspection of liquid crystal panel, adhesion of polarizer, and finalinspection.

The above inspection process of the liquid crystal panel includesinspection of optical characteristics, such as the inspections ofbrightness, luminance and response time. As the luminance and responsetime of liquid crystal displays will vary according to ambienttemperature, there is a need to perform the inspection of the ambienttemperature dependent luminance and response time.

The conventional measurement apparatus of liquid crystal panels is shownin FIG. 1. Referring to FIG. 1, the measurement apparatus 100 includesat least a reaction chamber 102 and a photometer 104. In this example, acolorimeter is used. The liquid crystal panel 108 is fixed in thereaction chamber 102 via the panel fitting apparatus 106. The photometer104 is used to measure the liquid crystal panel 108. Further, themeasurement apparatus 100 includes a temperature control apparatus (notshown). When the temperature variation is required, the temperature ofthe reaction chamber 102 is either increased or decreased to perform themeasurement.

However, the photometer 104 has a certain operating temperature range,for example, the operating temperature range for the above photometer(colorimeter) is about 23° C.±3° C. When the temperature variation ofthe liquid crystal panel 108 at either a higher or a lower temperaturehas to be measured, the temperature variation (increased or decreased)reflects the variation of the whole reaction chamber 102. As a result,the photometer 104 is frequently operated at a temperature out of theoperating temperature range. The precision and accuracy of themeasurement obtained therefrom is thus unreliable.

SUMMARY OF THE INVENTION

The present invention provides an ambient temperature control apparatusused for measuring a liquid crystal panel which can change the ambienttemperature surrounding the liquid crystal panel, so that themeasurement precision of the photometer is ensured.

The ambient temperature control apparatus used for measuring a liquidcrystal panel provided by the present invention comprises a bottomplate, a panel fitting apparatus, an external mask, and a temperaturecontrol device. The panel fitting apparatus is disposed on the bottomplate and is suitable for fixing a liquid crystal panel. The externalmask is detachably mounted to the bottom plate to form a cavity, inwhich only the panel fitting apparatus and the liquid crystal displayare enclosed. The external mask has at least one window allowing thephotometer to perform measurement on the liquid crystal panel. Thetemperature control device is mounted on the external mask to controlthe temperature variation of the cavity.

In one embodiment of the present invention, the ambient temperaturecontrol apparatus used for measuring the liquid crystal panel enclosesonly the liquid crystal panel therein. Therefore, when the ambienttemperature has to be changed for measuring the liquid crystal panel,the ambient temperature of the photometer is not affected. Therefore, anappropriate operating temperature of the photometer can be maintained toensure the measurement precision thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

These, as well as other features of the present invention, will becomemore apparent upon reference to the drawings wherein:

FIG. 1 shows a conventional measurement apparatus used for measuring theoptical characteristics of a display panel;

FIG. 2 shows a schematic drawing of an ambient temperature controlapparatus used for measuring a liquid crystal panel in one embodiment ofthe present invention;

FIG. 3 shows an external mask of an ambient temperature controlapparatus used for measuring a liquid crystal panel in one embodiment ofthe present invention;

FIG. 4 shows the local enlargement of an ambient temperature controlapparatus including a temperature control device used for measuring aliquid crystal panel in one embodiment of the present invention; and

FIG. 5 shows a schematic drawing of an ambient temperature controlapparatus used for measuring optical characteristics of a display panel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 2 shows a schematic drawing of an ambient temperature controlapparatus used for measuring a display panel.

In FIG. 2, the ambient temperature control apparatus used for measuringa display panel includes a bottom plate 202, an external mask 204, atemperature control device 206 and a panel fitting apparatus 208.

The panel fitting apparatus 208 is disposed on the bottom plate 202 forfixing the display panel 210.

The external mask 204 is detachably mounted on the bottom plate 202.When the external mask 204 is mounted on the bottom plate 202, only thedisplay panel 210 and the panel fitting apparatus 208 are enclosedwithin a cavity 212 formed thereby. The method for mounting thedetachable external mask 204 to the bottom plate 202 includes using apair of snapping type members or latches (not shown) installed on boththe external mask 204 and the bottom plate 202, respectively. Therefore,the user can easily attach and detach the external mask 204 from thebottom plate 202 as required.

The temperature control device 206 is mounted on the external mask 204.When the external mask 204 is assembled with the bottom plate 202 toform the cavity 212, the temperature control device 206 allows thetemperature of the cavity 212 to increase or decrease.

FIG. 3 shows a perspective view of the external mask 204 of the ambienttemperature control apparatus used for measuring a display panelaccording to the present invention.

As shown in FIG. 3, the external mask 204 includes a cap 204 a and aframe 204 b.

To comply with the shape of the liquid crystal panel 210, the cap 204 ais often made into a rectangular shape. The cap 204 a has at least onewindow, through which the photometer can measure the opticalcharacteristics of the liquid crystal panel 210. Preferably, the windowis made of light transparent material.

The cross section of the frame 204 b is identical to the shape of thecap 204 a, and one rim of the frame 204 b is connected to the perimeterof the cap 204 a. The cap 204 a and the frame 204 b can be formedintegrally or separately with the same or different material. Inaddition, a material with low reflectivity can be coated on an interiorwall of the external mask 204 to advantage the measurement. At least oneopening 204 c is formed on each side surface of the frame 204 b forinstalling the temperature control device 206.

FIG. 4 shows the local enlargement of an ambient temperature controlapparatus used for measuring the display panel.

In FIG. 4, the device for control temperature variation comprises atleast one cooler 206 a fitted in the opening 204 c of the frame 204 b.Heat sinks 206 b and 206 c are also installed at two sides of the cooler206 a. Further, fans 206 d and 206 e are further installed over the heatsinks 206 b and 206 c, respectively.

As the cooler 206 a is a semiconductor device generating heat andcooling at two sides via a conducting current, by controlling thedirection of the current flow, the direction for heating or cooling thecooler 206 a can be changed. For example, when the current flow of thecooler 206 a is controlled to direct the heating side towards theinterior of the cavity 212, the interior surface of the cavity 212 onthe same side as the heat sink 206 b and the fan 206 d is heated. Incontrast, the exterior surface of the cavity 212, that is, the same sideas the heat sink 206 c and the fan 206 e, is the cooling surface.Meanwhile, a heating effect can be obtained inside the cavity 212. Onthe contrary, if the current flow is reversed to the opposing direction,the interior surface of the cavity 212 becomes a cooling surface, whilethe exterior surface thereof becomes a heating surface. A cooling effectcan thus be obtained inside the cavity 212.

The installation of the heat sink 206 b and 206 c on the cooler 206 aallows the hot air (cold air) generated thereby to be diffused. The fans206 d and 206 e further enhance the diffusion of the hot air (cold air).According to specific design, the fan installed at the interior of thecavity 212 is so disposed to allow the air to be diffused inwardly, andthe fan installed at the exterior of the cavity is so disposed to allowthe air to be diffused outwardly with respect to the cavity 212.Therefore, the heating (cooling) effect can be optimized.

FIG. 5 schematically shows an ambient temperature control apparatus usedfor measuring optical characteristics of a display panel according tothe present invention. The ambient temperature control apparatus isdescribed in detail as follows.

The liquid crystal panel 210 mounted to a panel fitting apparatus 208 isdisposed on the bottom plate 202. The external mask 204 with thetemperature control device 206 is installed on the bottom plate 202 toform a cavity 212 enclosing the liquid crystal panel 210 and the panelfitting apparatus 208 therein. A thermal sensor 214 is installed tomeasure the temperature variation inside the cavity 212.

While performing measurement of the display panel using the ambienttemperature control apparatus as mentioned above, a required operatingtemperature can be input via a computer 218 as shown in FIG. 5. Acurrent supply 216 connected to the computer 218 is used to provide anappropriate current to the temperature control device 206 and thethermal sensor 214 to control the temperature of the cavity 212 to meetthe input required temperature. After controlling the temperature of thecavity 212 as required, the optical characteristics of the liquidcrystal panel 210 are measured using a photometer 220, for example, aBM-5A colorimeter. As the temperature of the photometer 220 is notaffected by the ambient temperature of the liquid crystal panel 210, aprecise measurement can be obtained.

In the above measurement apparatus, the light source required formeasurement is typically provided by a liquid crystal panel 210, whichincludes a backlight module. However, in the present invention, abacklight module (not shown) can also be installed on the bottom plate202 or the panel fitting apparatus 208, such that the liquid crystalpanel without the backlight module installed can also be measured.Further, the application range for the temperature control apparatus;and consequently the photometer, is broadened. On the other hand, astable light source is provided to reduce the error since using thebacklight module installed in each liquid crystal panel increases themeasurement error. Using the same light source effectively eliminatessuch measurement error.

Accordingly, since only the display panel is enclosed in the cavity ofthe ambient temperature control apparatus, the temperature control andvariation of the liquid crystal panel will not affect the ambienttemperature of the photometer. The temperature of the photometer canthus be maintained within an appropriate operating temperature, and themeasurement precision of the photometer is ensured.

Other embodiments of the invention will appear to those skilled in theart from consideration of the specification and practice of theinvention disclosed herein. It is intended that the specification andexamples are to be considered as exemplary only, with a true scope andspirit of the invention being indicated by the following claims.

1. A measurement apparatus for measuring optical characteristics of adisplay panel, comprising: a bottom plate; a panel fitting device,disposed on the bottom plate to fix the display panel thereon; anexternal mask, detachably mounted on the bottom plate to form a cavityenclosed by the bottom plate and the external mask, wherein the cavityencloses the panel fitting device and the display panel therein, theexternal mask having at least one window; a temperature control device,installed at the external mask to control temperature variation of thecavity; and a photometer, measuring the optical characteristics of thedisplay through the window.
 2. The measurement apparatus according toclaim 1, wherein the photometer includes a colorimeter.
 3. Themeasurement apparatus according to claim 1, wherein the external mask ismade of a transparent material.
 4. The measurement apparatus accordingto claim 1, the external mask further comprises: a cap, with a shapecomplying with the shape of the display panel, in which the window isformed; and a frame, with a cross section in the same shape as the cap,one rim of the frame being connected to a perimeter of the cap.
 5. Themeasurement apparatus according to claim 4, wherein the cap is made oftransparent material.
 6. The measurement apparatus according to claim 4,wherein the temperature control device is disposed in the frame.
 7. Themeasurement apparatus according to claim 1, wherein the temperaturecontrol device includes a cooler.
 8. The measurement apparatus accordingto claim 7, further comprises two heat sinks disposed at two sides ofthe cooler.
 9. The measurement apparatus according to claim 8, furthercomprising a fan installed over each of the heat sinks.
 10. Themeasurement apparatus according to claim 1, further comprising abacklight module disposed on the bottom plate.
 11. The measurementapparatus according to claim 1, further comprising a backlight moduledisposed on the panel fitting device.